Conventionally, protection against dust has been one of solutions for improvement of print quality of a printing medium to be printed by a printer. A compact printer for instant printing of pictures taken by a digital camera has been significantly developed with a proliferation of the digital camera. This printer is so compact that it hardly has a space in which the printing medium is moved forward and backward to the inside of the printer. Therefore, the printer needs to print on the printing medium, projecting the printing medium from a housing of the printer. This causes the entry of dust through a delivery port and the dust having adhered to the printing medium to be moved to a print head, which result in the deterioration in the print quality of the printing medium.
To prevent the entry of the dust through the delivery port for the printing medium, for instance, a paper discharge port protector of printer is disclosed in the Japanese patent application laid-open No. H8 (1996)-118755. The paper discharge port protector of printer comprises paper discharge guides which guide the paper discharged by discharge rollers to a paper discharge port, and a lid member which is freely movable between a close position for covering the paper discharge port and an open position for opening the paper discharge port so that paper can be discharged, and which guides the paper to be discharged upward through the paper discharge port.
The lid member which guides the paper upward through the paper discharge port in the '755 publication is effective in a use only for discharging the paper. However, in a printer for performing printing such as color printing on the paper as the printing medium by several times of the forward and backward feeding motions, dust tends to enter from above since there is an open space above the paper as the printing medium. Accordingly, the lid member cannot prevent the dust from adhering to the printing medium to be moved to the print head, which damages the print quality of the paper significantly.